Jellyfish tentacles inspire DNA chains to snag roving cancer cells

Jellyfish have inspired ideas for bird-safe wind turbines and artificial hearts. Now a team of researchers has drawn insight from a jellyfish’s tentacles to design a better way to capture dangerous cancer cells at large roving through the bloodstream.

Cancer cells are often most threatening when they break off from their original site and start invading other parts of the body, a process called metastasis. Current methods try to filter these cells out of the bloodstream for analysis by running a tiny sample of blood through a channel in a microfluidic device. The channel is coated with antibodies that can latch on to specific proteins in the cancer cells' surface. But they’re simply too short, just a few nanometers in length, to catch much in the flowing liquid, especially since whole cells can stretch 10 to 30 micrometers. (A micrometer is a thousand nanometers.)

The research published in this week’s Proceedings of the National Academy of Sciences looked to nature for a solution to this intractable problem. Study senior author Jeffrey Karp, a researcher at Brigham and Women’s Hospital, and colleagues at MIT and Harvard University thought about the way marine animals like jellyfish and sea cucumbers have long tentacles or arms with sticky patches that can snag tiny prey out of the water.

Thus inspired, they designed a device with long chains of DNA made out of aptamers, or repeating, 'sticky' blocks of DNA, that could specifically latch on to the protein tyrosine kinase 7, which is found in certain leukemia cells as well as in lung and colon cancers. They also cut the flow surface into a herringbone pattern, causing the flowing blood to swirl around rather than go straight through, making any cancer cells more likely to get snared by the DNA tentacles.

The researchers found they could push fluid through 10 times faster than previous research showed and that their bio-inspired device can catch up to four-fifths of target cells. Scaling the technology up could increase the flow rate a hundredfold and make it practical for future use in hospitals.

And since the tentacles can also be severed with enzymes, those captured cancer cells can be freed and recovered in the sample for later analysis, the study pointed out.

Since different aptamers can snag different types of proteins, the technology could prove useful for finding a number of different cancers and even free-floating fetal cells in a pregnant mother’s bloodstream, researchers say.

Identifying these cells earlier would help doctors personalize their patients' cancer treatment. And for leukemia patients, it could one day help avoid painful bone marrow sampling.